Add files_to_generate, lookup_file helpers

exe/protoc-gen-proto-plugin-demo

@@ -5,12 +5,12 @@ require "proto_plugin"
 
 class Demo < ProtoPlugin::Base
   def run
-    request.file_to_generate.each do |f|
-      name = File.basename(f, ".proto")
+    files_to_generate.each do |f|
+      name = File.basename(f.name, ".proto")
       add_file(path: "#{name}.txt", content: <<~TXT)
         Parameters: #{parameters}
 
-        This file was generated from #{name}.proto!
+        This file was generated from #{f.name}!
       TXT
     end
   end

lib/proto_plugin/base.rb

@@ -74,6 +74,34 @@ def parameters
       end
     end
 
+    # Returns an array of `Google::Protobuf::FileDescriptorProto` representing the files that
+    # were passed to `protoc` to be generated.
+    #
+    # @example `protoc --myplugin_out=. input_one.proto input_two.proto`
+    #   [
+    #     <Google::Protobuf::FileDescriptorProto: name: "input_one.proto">,
+    #     <Google::Protobuf::FileDescriptorProto: name: "input_two.proto">
+    #   ]
+    #
+    # @return [Array]
+    def files_to_generate
+      @files_to_generate ||= request.file_to_generate.filter_map do |filename|
+        lookup_file(name: filename)
+      end
+    end
+
+    # Finds a `Google::Protobuf::FileDescriptorProto` with the given `name` attribute.
+    #
+    # @return [Google::Protobuf::FileDescriptorProto]
+    # @return [nil] if the file was not found
+    def lookup_file(name:)
+      @index_by_filename ||= @request.proto_file.each_with_object({}) do |fd, hash|
+        hash[fd.name] = fd
+      end
+
+      @index_by_filename[name]
+    end
+
     # Returns the list of supported `CodeGeneratorResponse::Feature` values by the plugin. The returned
     # values are bitwise or-ed together and set on `response`.
     #

test/proto_plugin/base_test.rb

@@ -35,6 +35,19 @@ def run
       assert_equal("Hello World, Again!", @plugin.response.file.last.content)
     end
 
+    test "files_to_generate" do
+      files = @plugin.files_to_generate
+
+      assert_equal(1, files.count)
+      assert_instance_of(Google::Protobuf::FileDescriptorProto, files.first)
+      assert_equal("test/fixtures/simple/simple.proto", files.first.name)
+    end
+
+    test "lookup_file" do
+      refute_nil(@plugin.lookup_file(name: "test/fixtures/simple/simple.proto"))
+      assert_nil(@plugin.lookup_file(name: "test/fixtures/simple/missing.proto"))
+    end
+
     test "parameters" do
       plugin = TestPlugin.new(request: Google::Protobuf::Compiler::CodeGeneratorRequest.new(
         parameter: "foo=bar,bare",